Recording Characteristics and Crystallization Behavior of Ge/GeCu Bilayer Applied for Write-Once Blu-Ray Media

In this study, the Ge
₆₇
Cu
₃₃
(16 nm) layer and the Ge(3 nm)/Ge
₆₇
Cu
₃₃
(16 nm) bilayer were deposited by sputtering at room temperature and used as the recording films for write-once blue laser media. Compared with the crystallization temperature of Ge in the Ge
₆₇
Cu
₃₃
film (387.8-405.1 °C), the crystallization temperature of Ge in the Ge/Ge
₆₇
Cu
₃₃
bilayer can be further reduced to 347.7-382.8 °C. Moreover, the optical contrasts (@405 nm) of Ge
₆₇
Cu
₃₃
film and Ge/Ge
₆₇
Cu
₃₃
bilayer are determined to be 26.0% and 47.5%, respectively. This indicates that the Ge/Ge
₆₇
Cu
₃₃
bilayer is more suitable for the recording film of write-once blu-ray disc (BD-R) in comparison to Ge
₆₇
Cu
₃₃
film. The dynamic test shows that the optimum jitter value of the BD-R containing with the Ge/Ge
₆₇
Cu
₃₃
recording film is 7.4% for 2× recording speed, revealing this film is highly potential for the fabrication of blue laser media.